SCHEDULE IV - MORTGAGE LOANS ON REAL ESTATE - Mortgage Loan Activity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Movement in Mortgage Loans on Real Estate
Balance at the beginning of the period	$ 75,740	$ 103,440	$ 189,052
Additions during period
New loans	76,316	105,201	59,467
Other - deferral for collection of commitment fees, net of costs	1,706		385
Other - recoveries of bad debts, net of bad debt expense		199
Other - accretion of loan fees and discounts	676	1,592	6,841
Deductions during period
Collections of principal	(17,557)	(37,336)	(44,261)
Foreclosures	(127)	(92)	(708)
Cost of mortgages sold, net	(54,973)	(41,040)	(29,799)
Other - sale of mortgage loans			(77,121)
Other - bad debt expense, net of recoveries	(191)		(416)
Other - collection of commitment fees, net of costs		(739)
Other - reclassification from secured borrowings	(534)	(2,663)
Other - sale of commercial real estate loans (Note 7)		(52,822)
Balance at end of the period	$ 81,056	75,740	$ 103,440
Mortgage loans on real estate, non cash additions to commercial real estate loans		$ 966